Optionally stabilized drilling tool, and method of use

ABSTRACT

A hollow shaft is tapped and threaded at respective ends for engaging between a drill stem and a conventional cripple bit. A plurality of radially and longitudinally extending stabilizers are spaced longitudinally apart on said shaft. Each stabilizer is fixed to a collar mounted for rotation on the shaft, and retained thereon by fixed collars secured to the shaft overlapping end flanges of rotational collars. The shaft is recessed under each stabilizer to reduce friction of rotation thereon. Transverse holes are defined through the respective stabilizers to equalize pressures on the sides thereof. In rotational drilling, the stabilizers are randomly misaligned around the shaft to stabilize the drilling end portion of the drill string in its bore. If the bit changes direction to a side for any reason, the stabilizers are all aligned by a near side of the bore and cease to act as stabilizers. Rotational drilling is stopped and percussion drilling is begun with the crippled bit oriented by well known methods and equipment to correct to original direction. By resuming rotational drilling when correction is made the stabilizers become misaligned and stabilization is resumed.

United States Patent an Farris 1451 Apr. 29, 1975 1 1 OPTIONALLY STABILIZED DRILLING TOOL. AND METHOD OF USE Ralph J. Farris, 6111 Edwin St. New Iberia. La. 70746 122] Filed: Dec. 3. I973 [21] Appl. No.: 421.389

Related Application Data [76] Inventor:

[52] US. Cl. 175/61; 175/73 [51} lnt.C|. 1 ..E2lb7/04;EZl1J7/l8 [5N Field of Search 175/61. 57. 325. 73. 76. 175/87. 3172166/173. 31184 A [56] References Cited UNlTED STATES PATENTS 3.32-4.11)! 7/1943 Miller et a1. 175/61 X 2.745.635 5/1956 Zublin 175/76 2.873.091 M19159 D\\' er 175/61 3.087.558 4/1963 Dougherty. 175/317 X 1142.347 7/1964 Barnes 175/61 X 3.154.156 111/1964 Moore ct a1. 175/76 3.306.387 2/1967 Wi1liams.... 175/76 X 3.352.371) 11/1967 Livingston 175/73 3,363.7(14 1/1968 Farris et a1 175/61 X 3.7461108 7/1973 Hall 175/61 Primary EmmincrDavid H. Brown .41I()!'I1( Agent. or Firm-James B. Lake. Jr.

[57) ABSTRACT A hollow shaft is tapped and threaded at respective ends for engaging between a drill stem and a conventional cripple bit. A plurality of radially and longitudinally extending stabilizers are spaced longitudinall apart on said shaft. Each stabilizer is fixed to a collar mounted for rotation on the shaft, and retained thereon by fixed collars secured to the shaft overlapping end flanges of rotational collars. The shaft is recessed under each stabilizer to reduce friction of rotation thereon. Transverse holes are defined through the respective stabilizers to equalize pressures on the sides thereof. 1n rotational drilling. the stabilizers are randomly misaligned around the shaft to stabilize the drilling end portion of the drill string in its bore. 1f the bit changes direction to aside for any reason. the stabilizers are all aligned by a near side of the bore and cease to act as stabilizers. Rotational drilling is stopped and percussion drilling is begun with the crippled bit oriented by well known methods and equipment to correct to original direction. By resuming rotational dril ling when correction is made the stabilizers become misaligned and stabilization is resumed.

1 Claim. 4 Drawing Figures OPTIONALLY STABILIZED DRILLING TOOL. AND METHOD OF lSE This is a division. of application Ser. No. 291.12). filed 9/25/72. now U.S. Pat. No. 3.799.279.

The invention relates generally to apparatus for and method of drilling wells. and ntore particularly to drillstahilizers that are deactivated when drilling is off course and reactivated when drilling is back on course.

lt is old in the art to provide a plurality of stabilizers fixed rigidly to a tool in one or ntore rows spaced vertically apart. the tool being ettgaged in a drill-string between the drill-bit and the rest of the string. The fi\ed stabilizers resist any transverse movement of the drill either in leaving or returning to a desired drilling direction.

lt is an object of the invention to provide apparatus for and method of drill stabilization in drilling a well when on drilling course that destablizes when off drilling course.

Another object of the invention is to provide means for quickly changing a direction of drilling a well with out pulling the string to remove stabilizers.

Other objects and a fuller understanding of the inverttion may be had by referring to the following specification claims and drawings. in which:

Fl(i. l is a side elevation of the invention shown engaged between a cripple hit attd a drill stent and with stabilizers aligned Fl(i. 2 is a cross sectional view taken along section line 2-2 of Fl(i. l.

FIG. 3 is an end view of a cripple bit taken along transverse line 3-3. and

H0. 4 is a cross-sectional view taken along section 4-l of Fl(i. 2.

Referring to FIGS. l and 2. the invention comprises a hollow shaft l on which are alternately mounted fixed collars l2 and rotatable collars l-l. Stabilizers [6 are fixed to movable collars l4 and rotate therewith around shaft It]. A cripple bit [8 of conventional design is fixed to the lower end of shaft H). the upper end 24 of which is fixed to a drill stem 22.

Referring additionally to FIG. 4. shaft 10 defines a circumferential recess 26 under each rotatable collar 14 that extends longitudinally for the length of the associated stabilizer It: to reduce rotational friction. Flanges 28 extend from both ends of each rotatable collar l4 to overlap and rotatably engage shaft 10. Flanges 30. defined in the ends of fixed collars l2. are adopted to overlap adjacent flanges 28 to retain rotatable collars and associated stabilizers on shaft 10. Bolts 32 engage in congruent holes tapped itt fixed collars l2 and shaft 10 for rigidly securing thent together. Stabiiz ers 26 define holes 34 extending transversely therethrough for equalizing pressures on their respective sides.

A conventional cripple bit [8. recommended for use (til with the invention. comprises two toothed-drill-cones 36 mounted in the bit for rotation about ases spaced l2tl apart. A pressure no7zlc 38. connected with a supply of drill mud mixture through hollow shaft It). is spaced l2tl in the bit front each ofthe drill cones. Supplementary nozzles or outlets are spaced between said high pressure nozzles 38 and drill cones 36.

To use the invention in drilling. the invention is mounted in the drill-string as hereinbefore described. and the drill-string rotated in rotational drilling. The stabilizers 16. fixed to their respective rotatable collars l4. tend to turn therewith on shaft [0. in the direction of string and shaft rotation. actuated by a difference in friction between flanges 28 and said shaft and between llanges 28 and 30, to arrange themselves randomly about said shaft and space it equally front the walls of the bore, thereby stabilizing it in the bore. Mud pressure front nozzles 38 and 40 tending to initially move the stabilizers is quickly equalized on both sides of the stabilizers by holes 34 transversely defined therein.

If the drill bit moves off a drill course in spite of its stabilization. or for any reason it is desired to change the direction of drilling. the crippled bit is oriented in the bore with large nozzle 38 oppositely aligned front the desired direction for the bit to move. Rotational drilling having been halted for said orientation. percussive drilling is begun to pound the crippled bit up and down in its bore. The toothed drill cottes 36 will fracture material at the bottom of the bore on the side and in the direction to which said cones are oriented. Circa lating mud under pressure carries this material to the surface. If the drill bit moves off course. outer edges of stabilizers l6 contact a near side of the bore and are brought into alignment as shown in FIG. I. As stabilization depends on the random misalignment of the stabi lizers around shaft It). the bit is thus destabilized to change direction by the full diameter of the bore rather than by only a minor fraction thereof between stabilizer edges and bore wall. When the well bore hs been established in the new desired direction. the bit can be centered therein by reversing the orientation of cripple bit 18 briefly to bring it there. then percussive drilling is discontinued and rotational drilling is recommenced to thereby rotate the centered stabilizers out of alignment thereby stabilizing the drill bit in its drilling course.

What is claimed is:

l. Method of using an optionally stabilized drilling tool comprising the steps of: engaging a tool. having a plurality of non-symetrical stabilizer means mounted rotatably thereon. adjacent a non symetrical drill bit in a drill string; stabilizing said drill string by randomly displacing around said tool said plurality of stabilizer means by rotational drilling; and destabilizing said drill string by aligning said plurality of stabilizer means by percussive drilling with said bit. 

1. Method of using an optionally stabilized drilling tool comprising the steps of: engaging a tool, having a plurality of non-symetrical stabilizer means mounted rotatably thereon, adjacent a non-symetrical drill bit in a drill string; stabilizing said drill string by randomly displacing around said tool said plurality of stabilizer means by rotational drilling; and destabilizing said drill string by aligning said plurality of stabilizer means by percussive drilling with said bit. 